I saw "Postcards from Penguin" at a bookstore, and as a longtime reader of Penguin paperbacks, I wanted to like this set; but on closer inspection, I found it to be strikingly... monotonous.
The book description promises "100 postcards, each featuring a different and iconic Penguin book jacket," but this is not borne out by looking closer. In fact, a very large portion of all covers are nearly the same, a few basic templates with just the title & author names changed. In this dreary expanse, you thrill to see any graphic element, *anything* that departs from the template. I find it puzzling, actually, that the publishers could put together such a large collection with so *little* visual interest. I had the feeling that if I bought this set, I'd end up discarding half or two-thirds of the cards, because they wouldn't be interesting enough to send to anyone nor keep for myself.
The Penguin design schemes excelled (excel?) at separating the Penguin line from contemporaneous paperbacks, and at unifying all titles in its line, but lined up, many of them look exactly the same. I'd say, pass on this postcard set, unless you have particular nostalgia for certain covers, or perhaps you are playing witty games with your friends by sending them cards with insinuating book titles. Or, you might be thinking Pop Art, wishing to frame a grid of the cards, all the same except for the small change in title -- like Andy Warhol's Campbell soup cans. That could work.
If you look at surveys of Penguin's design, such as Phil Baines' "Penguin by Design: A Cover Story 1935-2005", you see that Penguin's design work was rather more diverse and creative than shown in these cards, which seem to largely reproduce Penguin covers from the 1940s' and 50's. Illustration, full color, and photography, in addition to typography, arrived at some point, and the Penguin line branched into alternately-designed lines such as Penguin Classics, with their now-famous pairings of book title with fine-art reproduction. Also distinguished by creative design were King Penguins, Penguin Great Ideas, and Pocket Penguins.
Note, this is only discussing covers (wrappers). A key aspect of Penguin's design quality over time has been the disciplined interior typography, first established and systematized by the Germany designer and typographer Jan Tschichold in the early 1940's. This was state of the art, the kind of discrete design work that helps the artifact work well, read well, and subtly convey a sense of quality and trustworthiness, without necessarily being noticed per se by readers. But, no matter, here we're reviewing the postcards, which only show covers.
So, take a close look at this if you're thinking of buying, and ask whether it's really the design showcase it claims to be. Phil Baines' book "Penguin by Design: A Cover Story 1935-2005" may be your better bet to really see Penguin's design achievements. Or you might have a local used or new bookstore that has a Penguin / pocket books-only section -- it's not so uncommon -- where you could survey the real thing.